Substation telephone-circuits.



B. o. wuus. SUBSTATION TELEPHONE CIRCUITS.

APPLICATION FILED AUG.23.I9-H1.

Patented Aug. 19, 1919.

M (a @QM bzwm UNITED STATES PATENT OFFICE.

BERNARD D. WILLIS, OF CHICAGO, ILLINOIS, ASSIGNOB TO AUTOMATIC ELECTRICCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SUBSTATION TELEPHONE-CIRCUITS,

Specification of Letters Patent.

PatentedAug. 19 1919.

T 0 all whom it may concern:

Be it known that I, Bnnnann D. Wrens, a citizen of the United States ofAmerica, and a resident of Chicago, county of Cook, and State ofIllinois, have invented certain new and useful Improvements inSubstation Telephone-Circuits, of which the following is aspecification.

My invention relates in general to substation telephone circuits but ismore particularly concerned with substation circuits for automatictelephone systems.

Briefly stated, the object of is to provide a circuit'arran ment wherebythere is introduced in a well own common battery substation circuit asubscribers impulse sender, also old in the art, with a view toproducing a more simple and ellicient substation arranghement forautomatic telephone systems than as hitherto been available.

The preferred form of the invention has been illustrated in the drawingby means of my invention two figures, of which Figure -1 is a detailedwirin diagram of an embodiment of the telephone invention whiclicomprises a desk set, while Fig. is a diagrammatic showing of thefundamental principles involved.

Referrin now to Fig. 2, the talking circuit is simi ar to thearrangement shown in the patent to Scribner, #669,710, the transmitter Tand a winding 4 of the induction coil I being in a bridge of the lineconductors 2 and 3, while the receiver R in series with the condenser Cand the other winding 5 of the induction coil I is connected in shunt ofthe transmitter. The above circuits of the transmitter and receiver arenormally open and are closed when the receiver is removed from thereceiver hook H. An inspection of the F1 ures will show that thetransmitter bridge includes the switch hook controlled contact springs 6and 1, while the receiver circuit includes the switch hook controlledcontact springs 8 and 9.

A signaling bridge, comprising the ringer M and the previously mcntionecondenser F, is provided as usual. It will be observed that this bridgeis not under the control of the switch hook.

The subscriber-s impulse sender or callin device, indicated by referencecharacter may be of the type shown in the patent to Blessing #1,ll9,394.It comprises essentially a pair of impulse sprin s 14 and 1."),controlled by a cam (not shown through the medium of a finger hole dial(also not shown), and a air of shunt springs 12 and 13- whic are closedwhenever the dial is turned from its normal position. The impulse sprin-14 and 15 are included in series with the line conductor 3 and theirfunction is to produce momentary interruptions of the line circuit forthe purpose of operatin the central oflice switchin devices. e shuntsprings S, when c osed, short-circuit the signaling and talking circuitbridges in order to reduce the impedance and resistance of the linecircuit, to prevent the interruptions being heard in the receiver, andto prevent tagvping of the bell during the transmission 0 impulses. Itis to be noted that the connections of these shunt springs are such thatif the calling device dial is o erated when the receiver is on the hookthe ine will not be short-circuited.

In Fig. 1, aspecific form of the circuit shown in Fig. 2 has been drawnin detail. The apparatus at the right of the drawing and comprising thetransmitter T, the receiver R, the switch hook H, and the calling deviceS constitutes a desk set telephone; w ile the apparatus at the left ofthe drawing and com risi the ringer M the condenser C an the inductioncoil l is sepa' rate from the said telephone and may mounted in theusual bell box. The telehone is provided with a terminal strip P in thebase thereof and the bell box is pro vided with a terminal strip P. Thevarious circuits are completedby means of a live conductor cord whichconnects the two terminal strips.

The advantageous arrangement of the various parts just described wouldnot be possible without adding additional cord conductors and othercomplications were it not for the new combination of circuits.

The operation of a substation instrument embodying my new circuits is asfollows: \Vhen the receiver is removed to initiate a call the switchhook controlled contact springs 6 and 8 come into engagement,respectivelv, with the contact springs 7 and 9, whereby the transmitterbridge and the receiver circuit are closed. Responsive t0 the closure ofthe transmitter bridge current is supplied to the transmitter rom abridged battery at the central oilice (not shown) over the followingpath. Line conductor '2, winding 4 of the induction coil best I,transmitter T, switch hook springs 6 and 7, and calling device impulsesprin s 14 and 15 to line conductor 3. The bri ge at the central oflicewhich includes the battery may also, in accordance with the usualpractice, include the controlling relay of an automatic switch, thecircuit of such relay including, therefore, the transmitter brid e atthe substation. It follows that the cafiing subscriber may by suitablymanipulating his calling device dial produce a series of interruptionsin the circuit of the controlling relay to bring about the operation ofthe said switch. It is important to note in this connection that as soonas the dial is turned from its normal position the substation loop iscompleted over a new path as follows: Line conductor '2, shunt s rin 12and 13, switch hook springs 6 and and impulse springs 14 and 15 to lineconductor 3. B the closure of the above circuit the signs ing andtalking circuit bridges are short-circuited for the purposes previouslymentioned. Successive operations of the dial will now result in theoperation of Suecessive switches at the.exchange, until the connectionis finall completed to the line of the called subscriber, it beinunderstood that all the switches are rovi ed with controlling relaybridges w ich with the exception of the bridge in the last switch, aresuccessively cut ofi from the line when their associated switches areoperated.

The connection *being completed, conversation may be held as desired.Since the operation of the talking circuits is well known it is not thouht to be necessary to devote any space to t e description of suchoperation herei It may be mentioned however, that the ringer M which isbridged across the line during conversation, should be of very highimpedance. When the receiver is replaced at the termination of theconversation the switch hook controlled contact springs are separated toremove the transmitter from the line and to open the receiver circuit.It is necessary to open the circuit of the receiver in addition to thatof the transmitter for otherwise the receiver together with the twowindings of the induction coil would form a shunt around the ringer M.The direct current 100 at the substation being broken by the rep acementof the receiver, current ceases to flow over the line conductors and theswitches at the central otlice are according] restored to normal in theusual and we] known manner. The substation is now in condition toreceive signaling currents which may come in over the line conductorsand traverse the ringer M and the condenser C, whereby the ringer isactuated to advise the subscriber of an incoming call.

It will be seen from the foregoing that L have devised new and simplecircuits whereby a common battery substation talking apparatus and asubscribers impulse sender are combined without detracting from thetalking qualities of the apparatus and without interfering with theeilicient operation of the impulse sender, thereby producing a highlydesirable substation equipment for automatic telephone systems.

Having described my invention, what I consider to be new and desire tohave protected by Letters Patent will be pointed out in the ap ndedclaims.

What claim as my invention is:

1. In a substation telephone set, a line circuit, a bridge of said lineincludin a transmitter, a second brid e of said fine includin areceiver, a third bridge of said line inc uding a condenser, said firstand second brid s normally open, means controlled by t e switch hook forclosing said normally open bridges, a calling device comprising a air ofimpulse springs in series with one me conductor, and a single pair ofshunt springseflective only when the receiver is removed toshort-circuit all of said bridges upon the operation of said callinlgdevice.

2. n a substation telephone set, a line circuit, bridges of said lineincluding, respectively, a transmitter, a receiver, and a signalingdevice, switch hook controlled means for closing the first of saidbridges, a sub'scribers impulse transmitter for sending current impulsesover the line circuit, a single pair of shunt springs in said impulsetransmitter closed when the same is 0 rated, and circuit connectionssuch that i the receiver is oil the hook the closure of sa d shuntfrrings is efl'ective to shortc 1rcu1t the sa i transmitter, receiver,and signaling device, and such that if the recelver is on the hook, theclosure of said shunt springs is effective to short-circuit saidtransmitter only.

t3. In a substation telephone set, a line circult; a transmitter and onewinding ofan induction coil in a bridge of said line, said bridgeincluding contact springs for closing the same a shunt circuit or saidtransmitter including a condenser, a second winding of said inductioncoil, and a receiver; a set of contact springs in the shunt circuitbetween the receiver and the said second coil wind-ing; a subscribersimpulse sender for transmittin current impulses over the line circuit;an a single pair of shunt springs ada ted to short-circuit thetransmitter bri ge when the said sender is operated.

fl. In a substation tele hone set, a line circu 1t, a ringer and a condiinser in a bridge of said line, a transmitter and a winding of aninduction coil in a second bridge of said line, a receiver and a secondwinding of said induction coil connected in series to form a conductingpath extending from the junction of the ringer and condenser to thejunction of the transmitter and said first winding, a normally openconnection in the trans lnitter bridge, a second normally openconnection in said conducting path, means for closing said connections,a subscribers impulse sender including make and break contacts fortransmitting current impulses over the line circuit, and a single air ofshunt springs in said sender adaptet to short-circuit the transmitterbridge when the said sender is operated.

5. In a substation telephone set, a line circuit, a transmitter inbridge of said line, a condenser, a winding of an induction coil, and areceiver in a second bridge of said line, a conductor common to saidbridges and including a second winding of said induction coil, anormally open connection in each bridge outside of the common conductor,means for closing said connections, a subscribers impulse sender, and asingle pair of shunt springs in said sender so connected that upon theoperation of said sender both the transmitter and receiver are shuntedif the receiver is oft the hook and the transmitter only if thereceiveris on the hook.

6.111 a substation telephone set, a line circuit, a transmitter inbridge of said line, a condenser, a winding of an induction coil, and areceiver in a second bridge of said line, a conductor common to saidbridges and including a second winding of said induction coil, anormally open connection in each bridge outside of the common conductor,means for closing said connections, a subscribcrs impulse sender, asingle pair of shunt springs in said sender so connected that upon theoperation of said sender both the transmitter and receiver are shuntedif the receiver is 011' the hook and the transmitter only if thereceiver is on the hook, a ter minal strip providing for the lineconnections and all connections of said condenser and induction coil, asecond terminal strip providing for all connections of the remainingapparatus, and a five conductor cord jolning said terminal strips overwhich all necessary circuits are completed as set forth.

7. In a substation telephone set, a line circuit, a t 'ansmitter and onewinding of an in duct-ion coil in a bridge of said line. said bridgeincluding contact springs for closing the same, a shunt circuit for saidtraiismitter including a condenser, a second winding of said inductioncoil, and a receiver; and a set of contact springs in the shunt circuitbetween the recelver and the said second coil winding, a calling devicecomprising a pair of impulse springs in series with one line conductorand a single pair of shunt springs effective only when the receiver isremoved to short circuit all of said bridges upon the ope 'ation of saidcalling device.

8. In a telephone substation, a line circuit including a transmitter andone winding of an induction coil in bridge thereof. contacts for closingsaid bridge across the line, a shunt circuit for said transmitterincluding the second winding of said induction coil. a second set ofcontacts for closing said shunt circuit and a receiver and condenserincluded in said shunt circuit on opposite sides of the said second setof contacts, a calling device comprising a pair of impulse springs inseries with one line conductor, and a single. pair of shunt springseffective only when the receiver is removed to short circuit all of saidbridges upon the operation ofsaid calling device.

Signed by me at Chicago, Cook county, State of Illinois, this 9th day ofAugust,

BERNARD I). \VILLFL

